1. Field of the Invention
This invention relates to a method and apparatus for processing molded synthetic resin materials, wherein a process is carried out on or parts are associated with a plurality of molded synthetic resin materials, which are conveyed one after another. This invention particularly relates to a method and apparatus for processing molded synthetic resin materials, wherein a process is carried out on or parts are associated with portions of a plurality of molded synthetic resin materials, which materials are conveyed intermittently, the portions being located in the vicinity of leading and tail ends of the plurality of the molded synthetic resin materials, which leading and tail ends are taken in the direction along which the plurality of the molded synthetic resin materials are conveyed.
2. Description of the Prior Art
In automatic processing lines, processes are carried out on or small parts are associated with predetermined portions of a plurality of molded synthetic resin materials, such as magnetic tape cassettes, which materials are conveyed intermittently. In such cases, positions of the molded synthetic resin materials are adjusted, and thereafter processes are carried out by processing means on the molded synthetic resin materials, the positions of which have been adjusted, or parts are associated by parts associating means with the molded synthetic resin materials, the positions of which have been adjusted.
In such automatic processing lines, it often occurs that a process is carried out by a single processing means simultaneously on portions of each of the plurality of the conveyed molded synthetic resin materials, such as portions in the vicinity of a leading end and a tail end of each molded synthetic resin material, which leading and tail ends are taken in the direction along which each molded synthetic resin material is conveyed. Such portions of each molded synthetic resin material are spaced far apart from each other. Also, it often occurs that parts are associated simultaneously by a single parts associating means with such portions of each molded synthetic resin material. As an example of such operations, a plurality of recognition holes are made through portions of a lower cassette half of a magnetic tape cassette, which portions are located in the vicinity of a leading end and a tail end of the lower cassette half. Such a perforating process is disclosed in, for example, Japanese Unexamined Patent Publication No. 2(1990)-30499.
FIG. 1 is a plan view showing a lower cassette half of a magnetic tape cassette. As illustrated in FIG. 1, in the disclosed process for making a plurality of recognition holes, recognition holes 2a, 2b, and 2c are made at a corner portion in the vicinity of a leading end of a lower cassette half 1. Also, recognition holes 2d and 2e are made at a corner portion in the vicinity of a tail end of the lower cassette half 1. The recognition holes 2a, 2b, 2c, 2d, and 2e are made simultaneously by a single perforating means. The positions, at which the recognition holes are made, are determined in accordance with the type and thickness of a tape accommodated in the magnetic tape cassette such that the type and thickness of the tape can be discriminated from others. It is necessary to carry out the process for making the recognition holes accurately.
However, dimensions of molded synthetic resin materials fluctuate due to differences among molds, differences among mold cavities, differences among lots, or the like. Therefore, in cases where a process is to be carried out by a single processing means accurately and simultaneously on portions of each of a plurality of molded synthetic resin materials, such as portions in the vicinity of a leading end and a tail end of each molded synthetic resin material, which portions are spaced far apart from each other, (as in the aforesaid process for making a plurality of recognition holes) or in cases where parts are to be associated accurately and simultaneously by a single parts associating means with such portions of each molded synthetic resin material, it is important which region of each molded synthetic resin material is taken as a reference for the position adjustment.
For example, in cases where the leading end of each molded synthetic resin material, which leading end is taken in the direction along which each molded synthetic resin material is conveyed, is employed as the reference for the position adjustment, a process can be carried out accurately on or parts can be associated accurately with the portion of the molded synthetic resin material in the vicinity of the leading end. However, because of fluctuations in the dimensions among the molded synthetic resin materials, the process cannot be carried out accurately o or the parts cannot be associated accurately with the portion of the molded synthetic resin material in the vicinity of the tail end. Such problems occur because the region employed as the reference for the position adjustment is spaced far apart from the portion of the molded synthetic resin material, on which the process is carried out or with which the parts are associated. Therefore, in order to eliminate the aforesaid problems, the region employed as the reference for the position adjustment and the portion of the molded synthetic resin material, on which the process is carried out or with which the parts are associated, should be as close to each other as possible.
However, when the region employed as the reference for the position adjustment and the portion of a molded synthetic resin material, on which a process is carried out or with which parts are associated, are set as close to each other as possible, problems described below occur. Specifically, in cases where the process is to be carried out on or the parts are to be associated with portions in the vicinity of the leading end and the tail end of each molded synthetic resin material, which is conveyed, in the manner described above, it is necessary that the region serving as the reference for the position adjustment is set at two regions (i.e., at the leading end and the tail end), and the position adjustment is carried out twice. However, if the region serving as the reference for the position adjustment is set at the leading end and the tail end, and the position adjustment is carried out twice, the process cannot be carried out by a single processing means simultaneously on the portions in the vicinity of the leading end and the tail end of each molded synthetic resin material in the manner described above. Also, the parts cannot be simultaneously associated by a single parts associating means with the portions in the vicinity of the leading end and the tail end of each molded synthetic resin material in the manner described above. As a result, the working efficiency cannot be kept high. Accordingly, a processing means or a parts associating means has heretofore been adjusted in accordance with fluctuations in the dimensions among molded synthetic resin material such that a process may be carried out simultaneously on or parts may be simultaneously associated with portions in the vicinity of the leading end and the tail end of each molded synthetic resin material, which portions are spaced far apart from each other. However, in such cases, the working efficiency cannot be kept high due to the operations for adjusting the processing means or the parts associating means.